The present invention relates to rolling mill systems of machines for the production of metal shapes and in particular to a rolling mill system capable of automatic configuration for the performance of a specified metal shape production job.
Rolling mills employ a set of movable rollers to shape metal billets into a variety of xe2x80x9cshapesxe2x80x9d such as angle, channel or rod of various diameters. A rolling mill is typically used as part of a rolling mill system, including, for example, an upstream reheat furnace or continuous casting machine providing heated billets, and a downstream water bath or Stelmor conveyor cooling the rolled material.
A given rolling mill system is capable of producing a wide variety of shapes by a changing in the operational parameters of the system including the roller dies, die separation, rolling speeds and temperatures. In a rolling mill system including multiple rolling mills, furnaces and cooling baths, the path through the machines may also be varied.
Reconfiguring a roller mill system is currently time consuming and expensive, and involves not only setting the operating parameters for each of the component pieces of equipment, but ensuring that there is consistency between those operating parameters. For example, speed through the water bath normally must match the desired rolling speed through the rolling mill. This step of ensuring a matching of operating parameters between the component machines of the rolling mill system complicates the selection of optimal through the rolling mill. This step of ensuring a matching of operating parameters between the component machines of the rolling mill system complicates the selection of optimal operating parameters and makes determining the trade-offs between the settings for different machines harder. This arises from the fact that although each machine may be modeled in a forward direction, that is, it may be determined how a change in rolling speed or die separation affects the billet temperature, the machines are not easily modeled in the reverse direction where there is no functional mapping. Thus, if a downstream water bath requires a different billet speed from a rolling mill, adjustment of the rolling mill presents a complex variety of alternatives.
For this reason, it is normally desired to minimize the changes in rolling mill setup, a desire that is at odds with economic demands to change the rolling mill setup frequently and quickly to respond to changing product demand. It would be beneficial to have a rolling mill system that could automatically and quickly organize itself to produce the desired product. It would further be desirable that this system accommodate a large variety of different types of rolling mill equipment.
The present invention provides a simplified bidding process for a rolling mill system in which prior to bidding, there is an exchange of operational constraints between the elements of the rolling mill system. In this exchange step, the autonomous controllers compare the ranges of their machine""s inputs and outputs to corresponding ranges of connected inputs and outputs of predecessor and successor machines in the rolling mill system. By internalizing these ranges, the bidding process is substantially simplified. Further to the extent possible, inconsistencies in the ranges are remedied by producing new ranges rather than individual values. In this way, local choice and optimization provided by the bidding process is preserved.
Specifically, the present invention provides an automatically configurable rolling mill system, including a rolling mill having entrance-receiving billets at an input temperature, a set of rolls rolling the received billets to change the billets by a rolling diameter as moved at a rolling speed, and an exit discharging the rolled billets at an output temperature. A rolling mill controller associated with the rolling mill includes an electronic memory holding data representing rolling mill constraints indicating constraints on the operation of the rolling mill, and inter-machine relationships indicating physical operating parameters of the rolling mill dependent on the physical operating parameters of other machines to which the rolling mill is connected. A controller further includes an electronic computer executing a stored program to receive a job plan describing a job to be performed by the rolling mill and other machines. An electronic computer then modifies the rolling mill constraints identified by the inter-machine relationships by the corresponding machine constraints of the other machines, and after this modification, exchanges bids and counterbids with the other machines proposing completion of portions of the job plan by the rolling mill and the other machines. Finally, the feasibility of the bids and counterbids are evaluated by the electronic computer against the modified rolling mill constraints.
Thus, it is one object of the invention to provide a more rapid convergence on a solution for organizing the machines of a rolling mill system by providing each autonomous control unit of the rolling mill system with information about constraints that may be imposed on the job plan by other machines. By bringing this information into each autonomous control unit, inefficient communication between the autonomous control units is minimized and a solution to the allocation of the job plan among the machines is more rapidly obtained.
The memory may hold multiple machine constraints and multiple inter-machine relationships identified to different material paths between machines. The machine constraints associated with a given material path are modified by the machine constraints of the other machines related by the inter-machine relationships associated with the given material path.
Thus, it is another object of the invention to address constraints imposed by adjacent machines without unduly limiting the solution sought by the autonomous control units. By segregating constraints according to machine paths, constraints applicable to one machine path are not necessarily imputed to the other machine paths.
The rolling mill system may also include reheat furnaces and water cooling baths also adapted to convey their constraints to other machines.
Thus, it is another object of the invention to provide an efficient negotiation process uniformly over many machines of the rolling mill system, all employing the autonomous control system of the present invention.
The foregoing and other objects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessary represent the full scope of the invention, however, and reference must be made to the claims herein for interpreting the scope of the invention.